Opsin-immunoreactive outer segments and acetylcholinesterase-positive neurons in the pineal complex of Phoxinus phoxinus (Teleostei, Cyprinidae)

I. Vigh-Teichmann, H. W. Korf, A. Oksche, B. Vigh

Research output: Contribution to journalArticle

61 Citations (Scopus)


The pineal complex of the teleost, Phoxinus phoxinus L., was studied light-microscopically by the use of the indirect immunocytochemical antiopsin reaction and the histochemical acetylcholinersterase (AChE) method. Opsin-immunoreactive outer segments of photoreceptor cells were demonstrated in large numbers in all divisions of the pineal end-vesicle and in the pineal stalk. Moreover, they were found in the roof of the third ventricle, adjacent to the orifice of the pineal recess as well as scattered in the parapineal organ. These immunocytochemical observations provide direct evidence of the presence of an opsin associated with a photopigment in the photosensory cells of the pineal and parapineal organs of Phoxinus. By means of the AChE reaction (Karnovsky and Roots 1964) inner segments of pineal photoreceptors, intrinsic nerve cells, several intrapineal bundles of nerve fibers, and a prominent pineal tract were specifically marked. The pineal neurons can be divided into two types: one is located near the pineal lumen, the other near the basal lamina. The latter perikarya bear stained processes directed toward the photoreceptor layer. A rostral aggregation of two types of AChE-positive nerve cells occurs in the ventral wall of the pineal end-vesicle. The main portion of the AChE-positive pineal tract, which lies within the dorsal wall of the pineal stalk, can be followed to the posterior commissure where some of the nerve fibers course laterally. A few AChE-positive pineal nerve fibers run toward the lateral habenular nucleus via the habenular commissure. In the region of the subcommissural organ single AChE-positive neurons accompany the pineal tract. The nerve cells of the parapineal organ exhibit a moderate AChE activity. These findings extend the structural basis for the remarkable light-dependent activity of the pineal organ of Phoxinus phoxinus.

Original languageEnglish
Pages (from-to)351-369
Number of pages19
JournalCell And Tissue Research
Issue number2
Publication statusPublished - Nov 1 1982



  • Acetylcholinesterase reaction
  • Opsin immunoreactivity
  • Parapineal organ
  • Pineal neurons
  • Pineal photoreceptors
  • Teleosts (Phoxinus phoxinus L.)

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Histology
  • Cell Biology

Cite this